The present invention relates to lasers, and more particularly to an improved interferometrically tuned laser resonator.
Laser resonators are often resonance tuned for maximum cavity gain by establishing an optical path repetitive for only a selected one of a plurality of different wavelengths emitted by a lasing material. One current method for tuning the laser resonator at one fluorescent line or wavelength while not affecting adjacent wavelengths utilizes a reflective device specially fabricated with dichroic coatings having the precise reflectance characteristics at the desired wavelength. Due to unavoidable variations in the characteristics during manufacture, the reflector must be hand picked for the desired wavelength. This makes the reflector very expensive as well as difficult to obtain. In another method, tuning is achieved with a prism which angularly disperses the laser beam according to wavelength, and a reflector selects one wavelength for repetitive traverse through the laser medium. In this method, the angular dispersion of the wavelengths is generally insufficient to single out one line among closely spaced lines, especially in the infrared band.